[chore] Add Container Service Fleet label to PRs touching fleet files (Azure#32878)

Author: serbrech

.github/policies/resourceManagement.yml

@@ -2774,6 +2774,16 @@ configuration:
         then:
         - addLabel:
             label: Container Service
+      - if:
+        - includesModifiedFiles:
+            files:
+            - specification/containerservice/Fleet.Management
+            - specification/containerservice/fleet
+            excludedFiles:
+            - ''
+        then:
+        - addLabel:
+            label: Container Service Fleet
       - if:
         - includesModifiedFiles:
             files: